1.\" Copyright (c) 1998 Doug Rabson 2.\" 3.\" All rights reserved. 4.\" 5.\" This program is free software. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" $FreeBSD: src/share/man/man9/device.9,v 1.7.2.4 2001/08/17 13:08:54 ru Exp $ 28.\" 29.Dd November 29, 2016 30.Dt DEVICE 9 31.Os 32.Sh NAME 33.Nm device 34.Nd an abstract representation of a device 35.Sh SYNOPSIS 36.Vt typedef struct bsd_device *device_t ; 37.Sh DESCRIPTION 38The device object represents a piece of hardware attached to the 39system such as an expansion card, the bus which that card is plugged 40into, disk drives attached to the expansion card etc. 41The system defines one device, 42.Dv root_bus 43and all other devices are created dynamically during 44autoconfiguration. Normally devices representing toplevel busses in 45the system (ISA, PCI etc.) will be attached directly to 46.Dv root_bus 47and other devices will be added as children of their relevant bus. 48.Pp 49The devices in a system form a tree. 50All devices except 51.Dv root_bus 52have a parent (see 53.Xr device_get_parent 9 ) . 54In addition, any device can have children attached to it (see 55.Xr device_add_child 9 , 56.Xr device_add_child_ordered 9 , 57.Xr device_find_child 9 , 58.Xr device_get_children 9 , 59and 60.Xr device_delete_child 9 ) . 61.Pp 62A device which has been successfully probed and attached to the 63system will also have a driver (see 64.Xr device_get_driver 9 65and 66.Xr driver 9 ) 67and a devclass (see 68.Xr device_get_devclass 9 69and 70.Xr devclass 9 ) . 71Various other attributes of the device include a unit number (see 72.Xr device_get_unit 9 ) , 73verbose description (normally supplied by the driver, see 74.Xr device_set_desc 9 75and 76.Xr device_get_desc 9 ) , 77a set of bus-specific variables (see 78.Xr device_get_ivars 9 ) 79and a set of driver-specific variables (see 80.Xr device_get_softc 9 ) . 81.Pp 82Devices can be in one of several states: 83.Bl -tag -width DS_NOTPRESENT 84.It Dv DS_NOTPRESENT 85the device has not been probed for existence or the probe failed 86.It Dv DS_ALIVE 87the device probe succeeded but not yet attached 88.It Dv DS_ATTACHED 89the device has been successfully attached 90.It Dv DS_BUSY 91the device is currently open 92.El 93.Pp 94The current state of the device can be determined by calling 95.Xr device_get_state 9 . 96.Sh SEE ALSO 97.Xr devclass 9 , 98.Xr driver 9 99.Sh AUTHORS 100This man page was written by 101.An Doug Rabson . 102